∊=⍥≢⌸⊆∪
⍤,
{1=≢⍵}⌸⊢⍤⌿∪
(1=⍧⍨)⍛⌿⍨
⊢~~∘≠⊢⍤/⊢
∊
∊⊆
⊢⍤/
⊢⌿⍨1=⍧⍨
⌿
⊢⍤⌿
⊢~~∘≠⍛/
~
⊢~~∘≠⍛⌿
f⍛g
⌸
∪
{⊃⊢⍤⌿/,⌿{⍺,⍨1=≢⍵}⌸⍵}
{⊃,/{⊂(1=≢⍵)/⍺}⌸⍵}
{⊃,/{⊂⍺⌿⍨1=≢⍵}⌸⍵}
,/
∊~⍨.⊣⌸